Taxonomy and Phylogeny

Goodeids (family Goodeidae) are named after the first known genus, Goodea, that was described by David Starr Jordanin 1880 in honour of George Brown Goode (13.02.1851-06.09.1896), his colleague and US american ichthyologist, who worked most of his time as a museum administrator. In 1872 Goode became the assistant of Spencer Baird, secretary of the Smithsonian Institute, and started to run the fish research program of the U.S. Fish Commision and the Smithsonian Institution in 1873. He effectively ran both till 1887. He authored many books and monographs and wrote more than 100 scientific reports and notes, most of them together with his Smithsonian colleague Tarleton Hoffman Bean. Goode had been a member of the National Academy of Sciences and the American Academy of Arts and Sciences and died of Pneumonia at Lanier Heights, near Washington as a young man at the age of 45 on Sept.6, 1896. His death left a void at the Smithsonian and together with the departure of Tarleton Bean the year before, research at the Smithsonian came to a stillstand. Goode had been universally liked and respected and had been very important for the American research activities concerning North American fish.

Prior to the revision of Lynne R. Parenti in 1981, two genera of egglaying fishes from Nevada had been aligned with Cyprinodontidae or placed in their own family, Empetrichthyidae. Meanwhile these genera with two species each and a few subspecies are recognized as a subfamily within Goodeids: Empetrichyinae. They are characterized by the lack of a pelvic skeleton. The genus Empetrichthys includes Empetrichthys latos from the Pahrump Valley in southern Nye County and the extinctEmpetrichthys merriami, Crenichthys actually the two species Crenichthys nevadae and Crenichthys baileyi with 5 subspecies, Cr. b. albivallis, Cr. b. baileyi, Cr. b. grandis, Cr. b. moapae and Cr. b. thermophilus. Phylogenetic results by Kyle Piller et al. (2017) revealed two lineages in each of the two species of Crenichthys with the need to split them both into two species. On the other hand, there was no genetical support for subspecies, so the future taxonomy of this genus will be built up by four species and no population with subspecies rank.

About 45 species mainly from the Mexican Plateau (Mesa Central) are classified within the subfamily Goodeinae. In contrary to the Empetrichthyinae, these species are euviviparous with an internal fertilization. Other synapomorphys of this monophyletic group are:

Anterior rays of anal of males shortened and slightly separated from rest of fin by a notch, producing a gonopodium-like pseudophallus

Eggs are small with little yolk

Embryos and newborn young with ribbon-like extensions from anal region associated with nutrition and respiration, termed trophotaeniae

We follow here Dominguez et al. (2010) and recognize four trives within this subfamily. The oldest one is the monogenetic tribe Characodontini with the genus Characodon and three described species: Characodon audax, Characodon lateralis and Characodon garmani. The last one (as long as it ever existed) became extinct in the late 1960s. The remaining two species are living distinct from the other Goodeid genera in the state of Durango, in the northern part of the Mesa Central. Habitats of these fish, mainly springs and little creeks, are located along the Río Mezquital in the Guadiana valley. This tribe was probably isolated by a vicariant event from the ancestors of all other Goodeids about 15.5 million years ago (Mya). The second and well defined tribe, Ilyodontini, is comprised of 3 genera, all of them living in rivers and creeks on the Pacific slope of the Mexican plateau in the states Jalisco, Colima, Michoacán, Morelos and México. The ancestor of this tribe was probably isolated from the ancestors of the other Goodeid genera about 10 Mya by the elevation of the Mesa Central. The genus Xenotaenia is monotypic. The only species Xenotaenia resolanae seems to be the most original form of this tribe. The sister group to it is the genus Ilyodon. Some trophical varieties, little genetic variation and geologigal events with river piracy phenomens make it hard to distinguish species. Actually two species - Ilyodon furcidens and Ilyodon whitei - are recognized. A third species, Ilyodon cortesae was described and is still widely recognized, but belongs definitely to Ilyodon whitei. Two more described species, Ilyodon xantusi and Ilyodon lennoni treated are either varieties and/or trophic morphs of whitei. Four ground-dwelling species are summarized in the third genus Allodontichtys: Allodontichthys hubbsi, polylepis, tamazulae and zonistius. The whole tribe has its origin probably in the area of the ríos Purificación and Marabasco. The theory says, that the ancestor of the genus Allodontichthys was isolated in the ríos Ameca and Armería area about 6.8Mya, the separation between Xenotaenia and Ilyodon with Xenotaenia remaining in the original habitat and Ilyodon being isolated in the Río Coahuayana area happened about 5.1 Mya. Recent events were expansion from Ilyodon whitei into the Río Balsas and a triple junction phenomen between the ríos Marabaso, Armerá and Coahuayna less than 2 Mya ago, that lead to a species exchange between those rivers. Later river piracy events connected the ríos Armerá and Coahuayana again and made the situation of species distribution even more difficult.

The former two tribes are clearly distinguishable from the rest of the Goodeinae. The coming species are closer related to each other, nevertheless they can be comprised in two tribes and two basal species, that were originally recognized as a tribe on its own, Goodeini, but recent studies don't support this theory. Both of them are (probably) monotypic. Ataeniobius with the only species toweri is endemic to the upper Rio Verde drainage in the State San Luis Potosí. Therewith it is the most eastern living species of Goodeids, and one of few inhabiting a river draining to the Atlantic ocean. It's origin is still not resolved but it might have been isolated from the ancestors of the tribe Girardinichthyini between 9.5 and 7.7 Mya. The second genus Goodea with probably one single, Goodea atripinnis is phylogenetically nearly as difficult as Ilyodon. Several species have been described and seized again. Even the species gracilis isn't recognized by all scientists. However, the gracilis form from Querétaro and San Luis Potosí is treated as endangered, but the remaining atripinnis form is definitely the most successful species among Goodeids, inhabiting nearly all areas and habitats of the Mesa Central. The reason for this success is unknown yet. The situation of Goodea is a mysterium as all representatives are closely related though they cover almost the whole Mexican plateau. Two theories exist. One says, the ancestor of Goodea, that was separated by the ancestors of the trive Chapalichthyini also about 9.5 to 7.7 Mya expanded to the ríos Ameca and Lerma much later and then covered the whole area quickly, the second says, it replaced a sister species (or species group) living in the Río Lerma area because it was more successful. This replacement must also have happened quite quickly. However, the history of these two species is not completely resolved. Anyway, they seem to be basal representatives and placed on the basis of a different tribe each.

The third tribe Chapalichthyini contains seven genera, one of them undescribed as the species eiseni and melanosoma, traditionally members of the genus Xenotoca, belong definitely to a distinct genus. Since 2016, with two more described species, doadrioi and lyonsi, and an undescribed species closely related to melanosoma, "Xenotoca" cf. melanosoma, five species are included in this genus. The name proposed by Webb (1998), Xenotichthys, has never been published officially and must be treated as nomen nudum. The genus is termed "Xenotoca" for the moment following Robert Rush Miller, published after his death 2005 and is the oldest one of the tribe, isolated in the Río Coahuayana basin about 6.8 Mya., and expanded about 5.1 Mya ago towards Nayarit. Xenoophorus is one of the monotypic genera of Goodeids, the only species is Xenoophorus captivus from the states of San Luis Potosí and Zacatecas. It was probably isolated in the headwaters of the Naranjo - Verde - protoriver about 6.3 Mya and later captured by the Río Pánuco system. The history of the next genera is not completely resolved, but they seem to have their origin in the Chapala proto-lake. The genus Zoogoneticus is comprised by three small and colourful species from Jalisco, Michoacán and Guanajuato. Zoogoneticus tequila from the Río Teuchitlán system was reported extinct in the wild immediately after its discovery in the early 1990s, but had been rediscovered in the 2000's close by the original habitat. After it disappeared there, too, a lot of efforts were undertaken to bring the species back. Since 2017, it is reintroduced in the springs of the Teuchitlán river. Zoogoneticus purhepechus had been split from Zoogoneticus quitzeoensis in 2008. These both species are barely distinguishable, but occur in different areas. Zoogoneticus tequila obviously was isolated in the Río Ameca area about 4.3 Mya whereas the ancestor of purhepechus remained. Later on it expanded eastwards with the Río Lerma and formed the third species, quitzeoensis in the Lago de Cuitzeo area. The same event that lead to Zoogoneticus tequila obviously gave origin to the monotypic genus Ameca with the popular Butterfly Splitfin, Ameca splendens. This species is also described from the Río Ameca and its tributary, the Río Teuchitlán, but can be additionally found in the Lago de Magdalena area (Almoloya spring) and had a population even in the Sayula valley. This one seems to be gone in 2006. A visually resembling species can be found within the genus Chapalichthys, namely pardalisfrom a spring pool at Tocumbo and the Presa San Juanico in Michoacán. This second population is sometimes recognized as a separate species (Chapalichthys peraticus) but belongs definitely to pardalis. The second species is Chapalichthys encaustus, distributed in the Lago de Chapala and some affluents like the Río Duero in Jalisco and Michoacán. A population of the Presa de la Vega in the Río Ameca area is treated as non - native, but was mentioned already in the 1950's. These two genera are closely related and were separated by about 3.9 Mya. The only descibed predator within Goodeids is Alloophorus robustus from the genus Alloophorus. These fish grow up to 15cm and are widely distributed in Guanajuato and Michoacán, but are not common. Populations from the Lago de Chapala area form a distinct to be described species, Alloophorus cf. robustus. It occurs in the state of Jalisco. The last genus Xenotoca contains one described species, Xenotoca variata and one undescribed form from the Cuitzeo basin, Xenotoca cf. variata. Xenotoca variata itself encompasses several lineages. The oldest one from the Lago de Chapala area is only known from the Los Negritos ponds east of the lake. Another one inhabits springs in the isolated Aguanaval river system in the far north. The biggest lineage encompasses populations form the Río Verde drainage in the west, over the northern Río Lerma affluents to the Río Pánuco. The fourth and last lineage inhabits the southern affluent of the Río Lerma, the Río Angulo including the Laguna Zacapu. The origin of the genus dates back about 4.4 Mya, the separation of both species 3.8 Mya.

The last tribe embraces two different groups, forming a monophyletic group each. Those two groups split about 6.9 Mya leading to one group originating in the Lago de Chapala area and one in the Lago de Cuitzeo area. The first group within the tribe Girardinichthyini can be called Allotoca-group and is formed by two genera. The smaller genus, Neoophorus with the single species regalis is sometimes included in the remaining genus Allotoca but is distinct enough to form a separate genus. Neoophorus regalis is restricted to the Cotija area south of the Lago de Chapala. Its ancestor splits from the one leading to Allotoca about 6 Mya. Allotoca is comprised by seven species. The most basal one is maculatafrom the endorheic Lago de Magdalena - Etzatlán area. About 3.3 Mya, the ancestor of Allotoca dugesiiandgoslineisplit from the other four ones, being comprised by acapuensis and the so - called diazi group being comprised by the species catarinae, diazi and meeki. While Allotoca goslinei lived in a tributary of the Río Ameca and is now treated as extinct in the wild, dugesii is distributed from the Lago de Chapala in the west to the Lago de Cuitzeo in the east. The remianing four species split about 2.1 Mya, mainly in a few distinct lake areas. The second group within the tribe Girardinichthyini could be called Girardinichthys-group. Four genera belong to this group, forming two groups. About 5.8 Mya a western group formed by two genera and distributed in the Lago de Cuitzeo area split from an eastern group of also two genera in the Atzlán paleolake. The western group led to the genus Skiffia with 3 described species, Skiffia francesae, lermae and multipunctata. Those species inhabit non current habitats in the states Jalisco, Michoacán and Guanajuato. Skiffia lermae from the Lago de Cuitzeo and adjacent drainages is clearly distinguishable from multipunctata and Skiffia francesae from the Lago de Chapala drainage and Río Ameca basin. Skiffia francesae might be a form of multipunctata or is at least very closely related. The nocturnal genus Hubbsina is comprised of the single species turneri. The in 2003 by Alfred Radda and Manfred Meyer described Girardinichthysireneae from the Zacapu lagoon belongs defintely to this genus and is highest probably the same species. The separation of Skiffia and Hubbsina happened probably about 4.5 Mya. The eastern group is formed by the genus Girardinichthysand two species. Girardinichthys viviparus was the first known species of Goodeids. First attempts to keep this fish in captivity might date back to 1772! It is restricted to the endorheic basin of Valle de México. The second species Girardinichthys multiradiatus inhabits waterbodies in the states Morelos, Michoacán and México. The ancestor of this genus split from the one of the monotypic genus Neotoca about 4.9 May. Neotoca bilineatawas former included in the genus Skiffia, but is closely related with Girardinichthys.